For several years now the 960px grid system (960.gs) has been designers' favorite pick to help structure and design web layouts. As screens and resolutions have gotten bigger, I've found that the 960 grid system does not always fit my needs. 20px gutters and only a 940px content area is a bit too small for the modern web. While designing Themify, I found a new grid layout that works quite well for designing in this day and age. If you've never heard of 960 I've detailed both it and this newer gird system below.
Follow up post: The Simpler Grid